Well, I find that Federal SV Target & Match (haven't tried the Ultra-Match) grades of ammo are the ONLY ammo that will reliably function my Ruger Mark II. I used to have a dickens of a time with failure-to-chamber (not really a failure to feed, it just wouldn't chamber all the way) when I was using other ammo. I went from gunsmith to gunsmith trying to figure it out, but noboby knew what was wrong...usually happened after 3-4 magazines, and was driving me bananas. I always had to look to see if I could see any brass showing, and if it was, push the bolt home with my hand. Tried stronger recoil springs, etc....nothing. Finally just jacked 2 mags of ammo through the gun without firing. When I got to the last cartridge, I had to PUSH the cartridge into the chamber, and not a light push, either. So I looked inside...there was a big ol' ring of the soft, gooey lube around the chamber at about the place where the mouth of the cartridge case came. Well, it wasn't so damn-all soft that it let the cartridge in easily; it was a real obstruction.
SO, I hied me to my local ammo emporium and investigated various brands of .22LR cartridges. I found the Federals had a nice HARD wax lube, which might not leave such a messy deposit.I bought a couple-three different grades and tried 'em out. It worked! Haven't had a problem since, and it's been 5 years and many bricks of ammo.
There MAY be other brands with a hard wax lube that would work equally well, but I've found what works, and I'm stickin' to it.